if you have Virgin Media Superhub 2, and have any old wireless router in a cupboard, plug that into one of the four modem mode sockets and have a second wifi network which should work for any iOS 11.4.1 device.
If you don't happen to have one, see if you can borrow one off a friend or member of the family.
I have an old Airport Express running my second home network, this way, and iOS 11.4.1 iPad runs just fine.
My iPhone and second iPad running iOS 11.4, are still running on VM wifi.( but , of course, will also run on my Airport Express network )
I am fortunate in having run a network cable to my first floor, a few years ago , so I have put my Airport Express upstairs; this has given me a better signal in some areas.
In fact, I shall probably keep this device running , even if Virgin Media , or another iSP comes up with a new wonderful modem/router, since the Airport Express consumes less than 3 watts.
Perhaps, soon, Apple will fix this annoying, frustrating nuisance. Next month, I think that iOS 12 will be forthcoming, but I won't be rushing to put that on my iOS 11.4 devices for a while.
The moral of the story is, don't throw away, or sell an old or spare router.
I am hesitant to ask for a Superhub 3 , from Virgin Media, not least because it is one of the most power-hungry routers on the market, and has quite a few VM-user people saying that it is not as good as SH2.